timer example

docs/examples/introduction/timers.css

@@ -0,0 +1,55 @@
+TimerWidget {
+    layout: horizontal;
+    height: 5;
+    background: $panel-darken-1;
+    border: tall $panel-darken-2;
+    margin: 1;
+    padding: 0 1;
+
+    transition: background 200ms linear;
+}
+
+TimeDisplay {
+    content-align: center middle;
+    opacity: 60%;
+    height: 3;
+}
+
+Button {
+    width: 16;    
+}
+
+#start {
+    dock: left;
+}
+
+TimerWidget.started {
+    opacity: 100%;
+    text-style: bold;
+    background: $success;
+    color: $text-success;
+    border: tall $success-darken-2;
+}
+
+TimerWidget.started #start {
+    display: none
+}
+
+TimerWidget.started #stop {
+    display: block
+}
+
+TimerWidget.started #reset {
+    visibility: hidden
+}
+
+
+#stop {
+    dock: left;
+    display: none;
+}
+
+
+Button#reset {
+    dock: right;
+}

docs/examples/introduction/timers.py

@@ -0,0 +1,84 @@
+from time import time
+
+from textual.app import App, ComposeResult
+from textual.layout import Container
+from textual.reactive import Reactive
+from textual.widgets import Button, Header, Footer, Static
+
+
+class TimeDisplay(Static):
+    """Displays the time."""
+
+    time_delta = Reactive(0.0)
+
+    def watch_time_delta(self, time_delta: float) -> None:
+        minutes, seconds = divmod(time_delta, 60)
+        hours, minutes = divmod(minutes, 60)
+        self.update(f"{hours:02.0f}:{minutes:02.0f}:{seconds:02.2f}")
+
+
+class TimerWidget(Static):
+    """The timer widget (display + buttons)."""
+
+    start_time = Reactive(0.0)
+    total = Reactive(0.0)
+    started = Reactive(False)
+
+    def on_mount(self) -> None:
+        self.update_timer = self.set_interval(1 / 30, self.update_elapsed, pause=True)
+
+    def update_elapsed(self) -> None:
+        time_delta = (
+            self.total + time() - self.start_time if self.started else self.total
+        )
+        self.query_one(TimeDisplay).time_delta = time_delta
+
+    def compose(self) -> ComposeResult:
+        yield Button("Start", id="start", variant="success")
+        yield Button("Stop", id="stop", variant="error")
+        yield TimeDisplay()
+        yield Button("Reset", id="reset")
+
+    def watch_started(self, started: bool) -> None:
+        if started:
+            self.start_time = time()
+            self.update_timer.resume()
+            self.add_class("started")
+        else:
+            self.update_timer.pause()
+            self.total += time() - self.start_time
+            self.remove_class("started")
+
+    def on_button_pressed(self, event: Button.Pressed) -> None:
+        button_id = event.button.id
+        self.started = button_id == "start"
+        if button_id == "reset":
+            self.started = False
+            self.total = 0.0
+            self.update_elapsed()
+
+
+class TimerApp(App):
+    def on_load(self) -> None:
+        self.bind("a", "add_timer", description="Add")
+        self.bind("r", "remove_timer", description="Remove")
+
+    def compose(self) -> ComposeResult:
+        yield Header()
+        yield Footer()
+        yield Container(TimerWidget(), TimerWidget(), TimerWidget())
+
+    def action_add_timer(self) -> None:
+        new_timer = TimerWidget()
+        self.query_one("Container").mount(new_timer)
+        self.call_later(new_timer.scroll_visible)
+
+    def action_remove_timer(self) -> None:
+        timers = self.query("Container TimerWidget")
+        if timers:
+            timers.last().remove()
+
+
+app = TimerApp(css_path="timers.css")
+if __name__ == "__main__":
+    app.run()

src/textual/_arrange.py

@@ -54,6 +54,7 @@ def arrange(
     for widgets in dock_layers.values():
 
         layout_widgets, dock_widgets = partition(get_dock, widgets)
+
         arrange_widgets.update(dock_widgets)
         top = right = bottom = left = 0
 
@@ -73,18 +74,18 @@ def arrange(
                 dock_region = Region(
                     0, height - widget_height, widget_width, widget_height
                 )
-                bottom = max(bottom, dock_region.height)
+                bottom = max(bottom, widget_height)
             elif edge == "top":
                 dock_region = Region(0, 0, widget_width, widget_height)
-                top = max(top, dock_region.height)
+                top = max(top, widget_height)
             elif edge == "left":
                 dock_region = Region(0, 0, widget_width, widget_height)
-                left = max(left, dock_region.width)
+                left = max(left, widget_width)
             elif edge == "right":
                 dock_region = Region(
                     width - widget_width, 0, widget_width, widget_height
                 )
-                right = max(right, dock_region.width)
+                right = max(right, widget_width)
             else:
                 # Should not occur, mainly to keep Mypy happy
                 raise AssertionError("invalid value for edge")  # pragma: no-cover
@@ -100,14 +101,17 @@ def arrange(
         layout_placements, arranged_layout_widgets = widget.layout.arrange(
             widget, layout_widgets, region.size
         )
+
         if arranged_layout_widgets:
             scroll_spacing = scroll_spacing.grow_maximum(dock_spacing)
             arrange_widgets.update(arranged_layout_widgets)
             placement_offset = region.offset
             if placement_offset:
                 layout_placements = [
-                    _WidgetPlacement(_region + placement_offset, widget, order, fixed)
+                    _WidgetPlacement(
-                    for _region, widget, order, fixed in layout_placements
+                        _region + placement_offset, layout_widget, order, fixed
+                    )
+                    for _region, layout_widget, order, fixed in layout_placements
                 ]
 
         placements.extend(layout_placements)

src/textual/dom.py

@@ -625,7 +625,7 @@ class DOMNode(MessagePump):
             query_selector = selector
         else:
             query_selector = selector.__name__
-        query = DOMQuery(self.screen, filter=query_selector)
+        query = DOMQuery(self, filter=query_selector)
 
         if expect_type is None:
             return query.first()

src/textual/geometry.py

@@ -629,8 +629,8 @@ class Region(NamedTuple):
         return Region(
             x=x + left,
             y=y + top,
-            width=max(0, width - left - right),
+            width=max(0, width - (left + right)),
-            height=max(0, height - top - bottom),
+            height=max(0, height - (top + bottom)),
         )
 
     @lru_cache(maxsize=4096)

src/textual/layouts/horizontal.py

@@ -46,9 +46,9 @@ class HorizontalLayout(Layout):
 
         x = Fraction(box_models[0].margin.left if box_models else 0)
 
-        displayed_children = cast("list[Widget]", parent.displayed_children)
+        displayed_children = [child for child in children if child.display]
 
-        for widget, box_model, margin in zip(displayed_children, box_models, margins):
+        for widget, box_model, margin in zip(children, box_models, margins):
             content_width, content_height, box_margin = box_model
             offset_y = (
                 widget.styles.align_height(

src/textual/widget.py

@@ -210,7 +210,7 @@ class Widget(DOMNode):
 
         """
         self.app._register(self, *anon_widgets, **widgets)
-        self.screen.refresh()
+        self.screen.refresh(layout=True)
 
     def compose(self) -> ComposeResult:
         """Yield child widgets for a container."""